TimelineGroupBy

Description#

Built-in bucketing modes plus the TimelineGroupingFn escape hatch. The three calendar modes read local date fields, so they stay correct across DST transitions where a day is 23 or 25 hours long - epoch division would silently split or merge those days.

'none' collapses everything into one synthetic group, which is how the organism renders an ungrouped role="list" without a second code path.